  
struct TreeNode {
   int val;
   struct TreeNode *left;
   struct TreeNode *right;
 };
#include<stdio.h>

struct TreeNode* invertTree(struct TreeNode* root){
    if(root==NULL)return root;
    struct TreeNode*left=invertTree(root->left);
    struct TreeNode*right=invertTree(root->right);
    root->left=right;
    root->right=left;
    return root;
}